Comment 20 for bug 1448418

Hello again. I think I have found a better workaround. First install the package dconf-editor if not already installed. Then open a terminal and type dconf-editor.
Navigate to apps -> indicator-session and check the box "supress-logout-restart-shutdown".
Close dconf-editor and since then, I have a working logout option (without confirmation dialogue of course).
It worked for me. Hope it also works for other.